Sensor-based Human Motion Tracking

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Sensor-based Human Motion Tracking

• Drew Walton
• CS525 Project
• Dr. Chow
• UCCS

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Overview

• Describe the reason for evaluating different
  types of monitoring technologies
• Define requirements for consideration as a good
  choice for monitoring body movement
• Introduce four technologies that are capable of
  performing the required functions
• Compare the selected technologies

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Reason for this project

• Interesting problem
• Remote monitoring of rehabilitative exercises!
• Curiosity
• What technologies are available?
• How are they being used for this application?
• Is there a problem to solve?
• Or am I too late?

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The Present Situation

• Numerous technologies exist to monitor the
  movement of the human body
• Mechanical
• Sonic
• Magnetic
• Accelerometers and gyros
• Video
• Combinations

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Requirements minimum

• Track all types of motion
• Bending, twisting, circular, jumping
• Track through realistic velocities of motion
• Accomplished by adequate sample rates
• Track through all ranges of motion
• No motions should be out-of-bounds
• Tracking must be accurate
• Accuracy must be fine enough to capture subtle
  movements

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Requirements Nice to have

• Non-bulky
• Must not interfere with the exercise
• Easy to wear
• Not all patients will ave same range of motion,
  strength or dexterity
• Easy to use
• Not all patients will be technical
• Reasonable price
• Doctors will want to own many
• Don't want them to disappear
• Rugged
• Software to display the movement

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Technology 1 Crossbow Mote

• Uses a combination of sonic and radio frequency
  transmissions
• Similar to counting the time between lightning
  and thunder
• Somewhat large circuit boards act as transmitters
  or receivers
• Currently best at tracking an entire person
• Multiple transmitter, single receiver approach

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Technology 1 Crossbow Mote

• Limitations
• Not very accurate
• Suffers from multi-path issues
• Too large to wear comfortably
• Can't use at all on small body parts
• Not able to make rapid samples
• Too slow to track quicker movements
• No software available to display the body moving
• One hand-held, or serial port needed for each
  receiver

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Technology 2 MIT Body Suit

• Uses ultrasonic transmissions, accelerometers and
  gyros
• Very accurate
• Uses 8 transmitters, 18 receivers all mounted on
  a body suit
• Must carry all equipment in a backpack
• Display software is available from somewhere

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Technology 2 MIT Body Suit

• Limitations
• Heavy backpack
• Can't target single area to track
• Suit may be difficult for some to put on
• There is potential for accumulated errors to
  result in inaccurate displays

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Technology 3 Moven Body Suit

• Very accurate
• Uses only inertial sensors, immune to noise
• Wireless transmission of data to base PC
• Body suit can be worn whole, or select upper or
  lower body
• Comes with display software

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Technology 3 Moven Body Suit

• Limitations
• Still is a suit some people may not be able to
  put on
• Cost is very high 50,000

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Technology 4 Vicon video

• The most accurate
• Uses 8 special video cameras all around the
  person being tracked
• No suit required! Patient wears small sensor dots
  for camera to pick up
• Display software is very nice
• Even has a language equivalent to Labanotation

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Technology 4 Vicon video

• Limitations
• Price! As much as 194,000
• A lot of equipment
• Cameras and mounting gear
• Receivers
• Computer
• A lot for a patient to set up

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Comparison

• Accuracy All have but crossbow, and MIT has
  cumulative error
• Bulkiness Vicon is best, but Moven suit is very
  good
• Easy to wear Vicon is dots placed using glue or
  velcro. Moven suit looks very good though
• Easy to use Moven seems easiest.
• Cost Crossbow is cheapest, but it doesn't really
  work. MIT is next, but isn't a product yet.
• Software Vicon is best, Moven is good. MIT is
  from unknown source

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References

• http//www.xbow.com (Crossbow Industries)?
• http//www.thinkartificial.org/artificial-intellig
  ence/whole-body-computer-interfaces/ (MIT Motion
  capture suit)?
• http//www.moven.com (Moven motion capture suit)?
• http//www.vicon.com (Vicon video motion capture
  system)?
• http//www.motion-capture-system.com/resources/har
  dware.html (Listing of many companies and their
  motion capturing technologies)?